Hairspring



Patented May 16, 1950 UNITED STATES FATENT OFFICE N Drawing. ApplicationJanuary 31, 1948, Serial No. 5,690. In Switzerland February 12, 1947 4Claims.

The work hitherto done in the province of ferro-nickels for hair-springshas had as its main purpose the endeavour to compensate for differencesof running which are due to variations of temperature, as exemplified bySwiss Patents Nos. 14,270, 15,526, 15,527, 54,876, 82,081 and 89,576.

Temperature variation is not however the sole cause of running faults ofWatches; variation of position from horizontal to vertical (flat tohung, according to the terms used by watch makers) occasions veryconsiderable disturbances, which are due, among other things, to theescapement itself, to the different friction of the pivots, etc. Tothese disturbances are also to be added the lack of isochronism of theoscillations of the hair-spring and balance assembly, the amplitude ofwhich is less in the vertical position than in the horizontal position.The hairsprings offer in fact an extremely serious defect when theoscillations are not isochronous and depend upon the amplitude.

The purpose of the present invention is to provide a solution of ametallurgical order for this difiicult problem. This solution will becomplete only if it conserves the properties of thermal compensation.

The compensating hair-springs used at present, consisting of austeniticferro-nickels hardened by simple or complex carbides, all give, in thehorizontal position, a loss of 8 to 25 seconds per day between the speedwhen the watch has just been wound-up and the speed after 24 hours, whenthe spring is relaxed and the amplitude of the oscillations is reduced.

Now, it has recently been found that it is possible to adjust theisochronism of such a hairspring at will, or even to modify it in thesense of a slight advance in the small oscillations, if the alloycomprises an addition of columbium (or niobium). This addition isalready distinctly perceptible at an amount of 0.1%, but it becomesenergetically effective in amounts of 1 to Columbium does not entail themanufacturing difiiculties which have been occasioned by all theadditions previously tried in the attempts to correct the loss of timein the small arcs of the carburised compensating ferro-nickels, andwhich have hitherto rendered this correction impossible.

From 0.1 to 1.5% it enables isochronism to be from 29 to 42% of nickel,from 4 to 10% chromium, from 1 to 5% of tungsten, from 0.1 to 2% ofvanadium, from 0.5 to 5% of manganese and silicon together, and from 0.5to 1% of carbon, the remainder being iron. In certain cases, thevanadium may be omitted.

Suitably proportioned within these limits, such an alloy thereforeenables an isochronous and thermally compensating hair-spring to bemanufacture'cl or even a hair-spring which, in the small arcs, revealsjust the very slight advance which is necessary in order to compensatefor the losses of time occasioned. by passing from the horizontalposition to the vertical position, while remaining thermallycompensating.

A watch provided with a hair-spring of the following composition:

Percent Nickel 29 to 42 Chromium 4 to 10 Tungsten 1 to 5 Vanadium 0.1 to2 Manganese and silicon 0.5 to 5 Carbon 0.5 to 1 Columbium 0.1 to 5 Ironremainder will be insensitive to variations of temperature and will showno difference of running between the horizontal position and thevertical position.

What I claim is:

1. An isochronically compensated hair spring for chronometers and thelike composed of a lferro-nickel alloy containing from 0.1 to 5% ofcolumbium, from 29 to 42% of nickel, from 4 to 10% of chromium, from 1to 5% of tungsten, from 0.5 to 5% of manganese and silicon together andfrom 0.5 to 1% of carbon, the remainder being Iron.

2. A spring formed of an alloy according to claim 1, further includingfrom 0.1 to 2% of vanadium.

3. An alloy comprising from 0.1 to 5% of columbium, from 29 to 42% ofnickel, from 4 to 10% of chromium, from 1 to 5% of tungsten, from 0.5 to5% of manganese and silicon, together, and from 0.5 to 1% of carbon, theremainder being iron.

4. An alloy according to claim 3 further including from 0.1 to 2% ofvanadium.

ERNEST DUBOIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,106,207 Guillaume Aug. 4, 19141,454,473 Guillaume May 8, 1923 2,373,490 Mohling Apr. 10, 1945

1. AN ISOCHRONICALLY COMPENSATED HAIR SPRING FOR CHRONOMETERS AND THELIKE COMPOSED OF A FERRO-NICKEL ALLOY CONTAINING FROM 0.1 TO 5% OFCOLUMBIUM, FROM 29 TO 42% OF NICKEL, FROM 4 TO 10% OF CHRONIUM, FROM 1TO 5% OF TUNGSTEN, FROM 0.5 TO 5% OF MANGANESE AND SILICON TOGETHER ANDFROM 0.5 TO 1% OF CARBON, THE REMAINDER BEING IRON.